Guide assembly

ABSTRACT

A guide assembly for a disc brake. The guide assembly includes a receiving portion of a brake carrier that receives a sleeve portion of a guide pin. The sleeve portion and receiving portion have corresponding non-circular cross-sectional profiles that restrict rotation of the sleeve portion relative to the brake carrier when the sleeve portion is received and aligned in the receiving portion. The present invention further relates to a disc brake that includes a brake carrier, a caliper, and at least one guide assembly and a method of manufacture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/174,102, filed Jun. 6, 2016, now abandoned, the disclosure of whichis hereby incorporated in its entirety by reference herein.

TECHNICAL FIELD

The present invention relates to a disc brake. In addition, the presentinvention relates to a guide assembly for a disc brake, to a method formanufacturing a guide assembly and to a disc brake incorporating a guideassembly.

BACKGROUND

Disc brakes are commonly used for braking heavy vehicles such as trucks,buses and coaches.

Disc brakes conventionally comprise a brake carrier, a caliper androtor. The brake carrier is arranged to carry brake pads on each side ofthe rotor. The caliper is slidably mounted on the brake carrier by twoor more guide assemblies, such that when the disc brake is actuated, thecaliper is able to slide with respect to the brake carrier. As thecaliper slides inboard, the brake pads are urged onto the opposing facesof the rotor in a clamping action and a braking action is effected.

A guide assembly typically comprises a guide pin along which the calipercan slide and a bore disposed in the caliper for receiving the guidepin. Typically, each guide pin comprises a smooth outer sleeve alongwhich the caliper slides and a bolt which extends through the sleeve andis screwed into a bore of the brake carrier to retain the sleeve.

This arrangement has been proven over many years of usage. However ithas been recognized that in certain operating conditions, specificallywhen a vehicle undergoes a significant number of forward and reversemovements, there is a risk that the bolt of the disc brake may rotateand loosen.

Previous attempts to solve this problem have utilized lock patches toinhibit rotation of the bolt.

However, the present inventors have recognized that this approach ineffect deals with a symptom of the problem rather than the cause. Thepresent inventors have also identified that the cause of the looseningbolt problem is the rotation of the sleeve and the rotation of thesleeve being frictionally transmitted into rotation of the bolt.

The present invention seeks to overcome or at least mitigate theproblems of the prior art.

SUMMARY

A first aspect of the invention provides a rotational fixing torotationally engage a guide sleeve and a brake carrier of a disc brake.By rotationally engaging the sleeve and brake carrier, the rotationalfixing is able to at least impede rotation of the sleeve relative to thedisc brake. Thus, the rotational fixing is able to at least restrictundesirable rotation of a sleeve caused by a changing torque as avehicle moves repeatedly forwardly and backwardly. The transmission ofrotation from the sleeve to the bolt and consequential loosening of thebolt is also restricted.

The rotational fixing for a disc brake may comprise: a sleeve portion ofa guide sleeve; and a receiving portion of a brake carrier for receivingthe sleeve portion; wherein the sleeve portion and receiving portionhave corresponding non-circular cross-sectional profiles such that, whenthe sleeve portion is received and aligned in the receiving portion,rotation of the guide sleeve relative to the brake carrier is thereby atleast restricted.

For the purposes of this present invention, a “non-circularcross-sectional profile” should be understood as meaning that therespective circumference of the sleeve portion and the receiving portionis not a complete circle. The corresponding non-circular cross-sectionalprofiles of the sleeve portion and the receiving portion may for examplecomprise a circular region and/or a linear region, may have a regularand non-circular shape, may have angular shape or a non-uniform shape.

The rotational fixing for a disc brake may comprise an interconnectionto inter-engage a guide sleeve and a brake carrier and thereby at leastrestrict rotation of the guide sleeve relative to the brake carrier.

The rotational fixing for a disc brake may comprise: a deformable sleeveportion of a guide sleeve; and a receiving portion of a brake carrier toreceive the sleeve portion; wherein the sleeve portion is deformable tobe received and form an interference fit with the receiving portion suchthat rotation of the sleeve relative to the brake carrier is thereby atleast restricted.

The rotational fixing for a disc brake may comprise: a sleeve portion ofa guide sleeve; a receiving portion of a brake carrier to receive thesleeve portion; and a friction enhancer to enhance the frictionalengagement between the sleeve portion and receiving portion, such thatwhen the sleeve portion is received by the receiving portion, rotationof the guide sleeve relative to the brake carrier is at leastrestricted.

A second aspect of the invention relates to a guide assembly for a discbrake comprising: a guide pin comprising a sleeve with a sleeve portion;a receiving portion of a brake carrier to receive the sleeve portion;wherein the sleeve portion and receiving portion have correspondingnon-circular cross-sectional profiles such that, when the sleeve portionis received and aligned in the receiving portion, rotation of the sleeverelative to the brake carrier is thereby at least restricted.

The sleeve portion of the sleeve may be a first end portion of thesleeve or a circumferential flange or rim at a first end of the sleeve.

The receiving portion of the brake carrier may be a recess disposed inthe brake carrier. Alternatively, the receiving portion may be a femalemember integrally formed or attached to the brake carrier. The receivingportion may be a male member protruding from the brake carrier andconfigured to receive at least a part of the sleeve portion.

The non-circular cross-sectional profile of the sleeve portion may bedefined by an outer edge of the sleeve portion. The sleeve portion maycomprise a circular outer edge region and a non-circular outer edgeregion. The circular outer edge region may be part of a circle (i.e., anarc). The non-circular outer edge region may be linear, substantiallyflat or angled, or a chord.

Likewise, the non-circular cross-sectional profile of the receivingportion may be defined by an inner edge of the receiving portion. Thereceiving portion may comprise a circular inner edge regioncorresponding to the circular outer edge region of the sleeve portionand a non-circular inner edge region corresponding to the non-circularouter edge region of the sleeve portion. The circular inner edge regionmay be part of a circle (i.e., an arc). The non-circular inner edgeregion may be linear, substantially flat or angled, or a chord.

The non-circular inner edge region of the receiving portion may belocated at any angular orientation with respect to the brake carrier.Preferably, it is arranged in a low-stress region of the brake carrier.This, in turn, may be dependent on the orientation in which the brakecarrier is installed with respect to the axle of the vehicle.

The receiving portion of the brake carrier may further comprise a firsttransition inner edge region at a first junction between the circularinner edge region and the non-circular inner edge region. The firsttransition inner edge may, for example, be a first curved cornerextending between a first end of a linear inner edge region and a firstend of a circular inner edge region of the receiving portion.

To counter rotational torque acting on the sleeve in a first rotationaldirection, the first transition inner edge region may be configured suchthat, when the sleeve portion is received and aligned in the receivingportion, the first transition inner edge region is able to abut thesleeve portion so as to restrict rotation of the sleeve portion in thefirst rotational direction. For example, the first transition inner edgeregion may be configured to abut the sleeve portion so as to at leastrestrict rotation of the sleeve portion in a clockwise direction.

The sleeve portion of the sleeve may further comprise a first chamferedouter edge region at a first junction between the circular outer edgeregion and the non-circular outer edge region. The first chamfered outeredge region enhances the surface contact area between the sleeve portionand the first transition inner edge region and this, as a consequence,helps to further impede the rotation of the sleeve portion in the firstrotational direction.

The receiving portion of the brake carrier may comprise a secondtransition inner edge region at a second junction between the circularinner edge region and non-circular inner edge region. The secondtransition inner edge region may, for example, be a second curved cornerextending from a second end of a linear inner edge region to a secondend of a circular inner edge region.

To counter rotational torque acting on the sleeve in a second rotationaldirection (opposite to the first rotational direction), the secondtransition inner edge region may be configured such that, when thesleeve portion is received and aligned in the receiving portion, thesecond transition inner edge region is able to abut the sleeve portionso as to restrict rotation of the second rotational direction. Forexample, the second transition inner edge region may be configured toabut the sleeve portion and thereby at least restrict rotation of thesleeve portion in an anti-clockwise direction.

To enhance the abutment of the sleeve portion by the second transitionregion and thereby further impede the rotation of the sleeve portion inthe second rotational direction, the sleeve portion may further comprisea second chamfered outer edge region at a second junction between thecircular outer edge region and the non-circular outer edge region.

To mount the guide pin on the brake carrier, the guide pin may comprisea fastener and the guide assembly may further comprise a bore disposedin the brake carrier to receive the fastener. Preferably, the fasteneris configured to extend through the sleeve and the bore is arranged inthe receiving portion. The bore may be arranged centrally oreccentrically in the receiving portion. The fastener may be a bolt, forexample a threaded bolt and the bore disposed in the brake carrier mayhave a complimentary threaded bore.

The corresponding non-circular cross-sectional profiles of the sleeveportion of the sleeve and the receiving portion of the brake carrier notonly help to restrict rotation of the sleeve but also advantageouslyhelp to minimize operator error when installing or servicing the discbrake. For example, if the operator fails to correctly align thecorresponding non-circular regions of the sleeve portion and thereceiving portion, but nevertheless tightens the fastener, the guide pinwill not extend normal to the brake carrier as required. Thus, theoperator will not be able to assemble the caliper because the guide pinwill be out of alignment to the complimentary bore of the caliper.

A third aspect of the invention provides a disc brake comprising a brakecarrier, a caliper and at least one guide assembly according to thesecond aspect of the invention for slidably mounting the caliper withrespect to the brake carrier.

A fourth aspect of the invention provides a method for manufacturing areceiving portion of a brake carrier for receiving a sleeve portion of aguide sleeve. If the receiving portion is a recess disposed in the brakecarrier, the method of manufacture may comprise cutting a recess in thebrake carrier with a circular inner edge region and a non-circular inneredge region.

The method may further comprise: moving a cutting tool in a circularpath to define the circular inner edge region; and moving the cuttingtool in a non-circular path to define the non-circular inner edgeregion.

If the non-circular inner edge region is a linear inner edge region,then the non-circular path is a linear path.

The method may further comprise moving the cutting tool from thecircular path to the non-circular path to define a transition inner edgeregion between the circular inner edge region and the non-circular inneredge region.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 is an isometric view showing a disc brake according to thepresent invention with a preferred embodiment of the guide assembly;

FIG. 2 is an enlarged isometric cross-sectional view showing thepreferred embodiment of the guide assembly;

FIGS. 3a, 3b and 3c are different views showing the sleeve of thepreferred guide assembly;

FIG. 4 is a front view of the brake carrier showing the recess of thepreferred guide assembly;

FIGS. 5a to 5g is a series of views showing how a circular cutting toolmoves in a circular path to cut the first circular inner edge region ofthe recess of the preferred guide assembly;

FIGS. 6a and 6b is a front view of the brake carrier and an enlargedview showing the recess of the preferred guide assembly;

FIG. 7 is an exploded perspective view of the preferred guide assemblyshowing the guide pin and the brake carrier;

FIG. 8 is a top view of the preferred guide assembly showing the guidepin mounted on the brake carrier;

FIGS. 9a to 9c are schematic views showing the correspondingcross-sectional profiles of the sleeve portion and receiving portion foralternative embodiments of the guide assembly; and

FIGS. 9d to 9g are schematic views showing interconnections foralternative embodiments of the guide assembly.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

Referring to FIGS. 1 to 9 g, a disc brake according to the presentinvention is indicated generally at 1. The disc brake comprises a brakecarrier 10. The brake carrier carries an inboard brake pad 12 a and anoutboard brake pad 12 b. A rotor 14 (shown in part) is positionedbetween the brake pads and is rotatable about an axis R. A caliper 16 isslidably mounted with respect to the brake carrier by at least one guideassembly. In the embodiment depicted, the disc brake comprises two guideassemblies 18 a, 18 b. Each of the two guide assemblies is a guideassembly according to the preferred embodiment of the invention.

Each guide assembly comprises a guide pin 20 along which the caliper 16can slide and a bore 22 disposed in the caliper for receiving the guidepin. In the embodiment depicted, one of the guide pins 20 a is shorterthan the other guide pin 20 b in order to accommodate vehicleinstallation constraints.

The guide pin 20 comprises a fastener 24 to attach the guide pin to thebrake carrier 10. The fastener is received by a complimentary bore 26disposed in the brake carrier.

The guide pin 20 further comprises a sleeve 28 at least substantiallysurrounding the fastener 24 and over which the caliper 16 slides. Thesleeve is a hollow, thin walled tube. The outer surface of the sleevemay be coated with PTFE (polytetrafluoroethylene) or any other suitablematerial to aid the sliding action of the caliper along the guide pin.The sleeve comprises a main body 30, a first end 32, a second end 34 anda bore hole 36 extending from the first end to the second end to receivethe fastener.

The bore 22 disposed in the caliper to receive the guide pin is anelongate hole extending from a first side (inboard) to the second side(outboard) of the caliper 16.

During use, the guide pin 20 will be subject to dynamic loads. Tocounter rotational torque, the guide assembly of the present inventionfurther comprises a rotational fixing to rotationally engage the sleeve28 and the brake carrier 10 and thereby at least restrict rotation ofthe sleeve about its longitudinal axis. By rotationally engaging thesleeve and the brake carrier, the rotational fixing helpfully minimizesor avoids undesirable rotation of the sleeve.

By restricting the rotation of the sleeve relative to the brake carrier,the transmission of rotation from the sleeve to the fastener is alsorestricted. Thus, the subsequent risk of loosening the fastener from thebrake carrier is advantageously reduced.

A rotational fixing for the disc brake may comprise a sleeve portion ofthe sleeve and a receiving portion of the brake carrier for receivingthe sleeve portion. The sleeve portion may comprise an end portion ofthe sleeve, a circumferential flange or rim of the sleeve. The receivingportion may comprise a recess disposed in the brake carrier, a femalemember integrally formed or attached to the brake carrier or a malemember protruding from the brake carrier.

The sleeve portion and the receiving portion may comprise correspondingnon-circular cross-sectional profiles. As a consequence, the sleeveportion and receiving portion have a must-fit arrangement. The sleeveportion must be correctly aligned relative to the receiving portion forit to fit into the brake receiving portion. When the sleeve portion islocated in the receiving portion, rotation of the sleeve relative to thebrake carrier is restricted.

In the preferred embodiment of the guide assembly as shown in FIGS. 1 to8, the sleeve portion of the rotational fixing is a circumferentialflange 40 arranged at the first end of the guide sleeve. Thecross-sectional profile of the flange is defined by an outer edge of theflange. In this embodiment, the flange has a non-circularcross-sectional profile comprising two profile regions. The profile ofthe flange has a first circular outer edge region 42 and a second flatouter edge region 44.

The desired cross-sectional profile of the flange may, for example, bemanufactured by removing a segment of a circular flange of aconventional sleeve. The flange may be manufactured using anyconventional cutting, milling or machining techniques, using for examplea CNC (Computer Numerically Controlled) lathe or CNC milling machine. Acutting tool may be moved in a linear path to cut away the segment ofthe circular flange so as to form a flange with a first circular outeredge region and the second flat outer edge region. By way of example, acircular flange with a diameter of approximately 39.95 mm may be cutalong a chord to remove a segment with a depth of approximately 1.75 mmsuch that the resulting flange has a first circular outer edge regionwith a radius of approximately 19.97 mm and a second flat outer edgeregion with a radius of approximately 18.25 mm

In the preferred embodiment of the guide assembly, the receiving portionof the rotational fixing is a recess 46 disposed in the brake carrier toreceive the flange of the guide sleeve. The cross-sectional profile ofthe recess is defined by an inner edge of the recess. The inner edge hasa corresponding non-circular cross-sectional profile to the flange. Thenon-circular cross-sectional profile of the recess comprises a firstcircular inner edge region 48 and a second flat inner edge region 50.

The flat inner edge region 50 of the recess may be located at anyangular orientation with respect to the brake carrier. The flat inneredge region is preferably arranged in a low-stress region of the brakecarrier. The orientation of the flat inner edge region may be determinedby the orientation of the brake carrier with respect to the axle of thevehicle. In the preferred embodiment depicted in FIGS. 1 to 8, the flatinner edge region is arranged at a 6 o'clock orientation to the brakecarrier.

The recess may be manufactured with the desired cross-sectional profileusing any conventional cutting, milling or machining techniques, usingfor example a CNC lathe or CNC milling machine. The recess may be cut inthe brake carrier by moving a cutting tool in a circular path to definethe circular inner edge region. FIGS. 5a to 5g show how a rotatingcutting tool may be moved sequentially in a circular path to cut arecess with the circular inner edge region. The rotating cutting toolmay also be moved along a linear path to cut the flat inner edge region.By way of example, the recess may be cut in the brake carrier using acircular cutting tool with a diameter of 25 mm whereby the cutting toolmay be moved along a circular path to cut a circular inner edge regionwith a radius of approximately 20 mm and the cutting tool may be movedalong a linear path to cut a flat linear edge region with a radius ofapproximately 18.95 mm and a flat edge length of approximately 12.5 mm.

As the cutting tool moves from the circular path to the linear path andsubsequently the linear path to the circular path, transition inner edgeregions are formed between the circular inner edge region and the flatinner edge region. In the embodiment, the recess comprises a firsttransition inner edge region 52 at a first junction between the circularinner edge region and the flat inner edge region. As can be seen in FIG.6b , the first transition inner edge region 52 is a curved cornerextending between the first end of the flat inner edge region and thefirst end of the circular inner edge region. The recess also comprises asecond transition inner edge region 54 at a second junction between thecircular inner edge region and the flat inner edge region. The secondtransition inner edge region 54 is a curved corner extending between thesecond end of the flat inner edge region and the second end of thecircular inner edge region.

The dimensions and configuration of the sleeve portion and recess areselected such that, when the sleeve portion is received and aligned inthe recess, the first transition inner edge region 52 is able to abutthe sleeve portion and thereby at least restrict the rotation of thesleeve portion in a first rotational direction—for example, theclockwise direction. The first transition inner edge region 52preferably mates and abuts the sleeve portion at a first junction 56between circular outer edge region 42 and the flat outer edge region 44.

Likewise, the second transition inner edge region 54 is able to abut thesleeve portion and thereby at least restrict the rotation of the sleeveportion in a second rotational direction—for example, the anti-clockwisedirection. The second transition inner edge region 54 preferably matesand abuts the sleeve portion at a second junction 58 between thecircular outer edge region 42 and the flat outer edge region 44.

The abutting action of the sleeve relative to the brake carrier dependson the tolerances, configuration and dimensions of the sleeve portionand recess. By way of example, the guide assembly may be configured toprovide an abutting action that is able to restrict the rotation of thesleeve relative to the brake carrier to up to a maximum of approximately10 degrees. The guide assembly may alternatively be configured toprovide an abutting action that is able to restrict rotation to up to amaximum of approximately 5 degrees, to up to a maximum of approximately3 degrees or up to a maximum of approximately 1 degree.

To enhance the mating contact between the sleeve portion and thetransition regions of the receiving portion, the flange 40 may bechamfered at the junctions between the circular outer edge region 42 andflat outer edge region 44. The sleeve portion may comprise a firstchamfered outer edge region 60 at the first junction 56 between thecircular outer edge region 42 and the flat outer edge region 44 and asecond chamfered outer edge region 62 at the second junction 58 betweenthe circular outer edge region 42 and the flat outer edge region 44. Thefirst chamfered outer edge region 60 improves the surface contact areabetween the flange 40 and the first transition inner edge region 52. Thesecond chamfered outer edge region 62 improves the surface contact areabetween the flange 40 and the second transition inner edge region 54. Byincreasing the surface contact area, the abutting effect of thetransition edge regions is improved and the rotation of the sleeve 28 isfurther restricted.

In the preferred embodiment of the guide assembly as shown in FIGS. 1 to8, the fastener 24 for attaching the guide pin to the brake carrier is athreaded bolt and the bore 26 for receiving the fastener in the brakecarrier is a threaded bore. The bore 26 is located in the recess 46 forreceiving the sleeve portion. The bore may be centrally located oreccentrically located in the recess. The bore may be manufactured by anyconventional drilling techniques.

To mount the guide pin on the brake carrier and rotationally engage thesleeve and the brake carrier, the bolt 24 is extended through the borehole 22 of the sleeve, the flange 40 of the sleeve is located in therecess 46 with the profile regions aligned so as to form a rotationalengagement between the sleeve and the brake carrier, and the bolt isscrewed into the bore 26 in the brake carrier.

When attached to the brake carrier 10, the guide pin 20 extends in anaxial direction A. Direction A is parallel to an axis R of rotation ofthe rotor 14 and parallel to the transverse axis of the disc brake. Thecaliper will be mounted on the guide pin by locating the guide pin inthe caliper bore 22 and sliding the caliper along the guide pin sleeve.

When fully assembled, the disc brake as depicted in FIG. 1 can beactuated. An air actuator (not shown) is provided to move the inboardbrake pad 12 a into frictional contact with the rotor. When the inboardbrake pad 12 a is pushed towards and contacts the rotor, the caliperslides inboard along the guide pin. As the caliper slides inboard, itmoves the outboard brake pad 12 b towards the rotor. Hence, the rotorbecomes clamped between the inboard and outboard brake pads and therotation of the rotor is frictionally inhibited.

However, due to the corresponding non-circular cross-sectional profilesof the flange and recess, the disc brake can only be assembled orserviced if the profile regions of the flange and recess are properlyaligned when first locating the flange in the recess. If the flange andrecess are not properly aligned, the guide pin will not extend in thecorrect direction from the brake carrier. As a result, an operator willnot be able to mount the caliper on the guide pin. Therefore, it isapparent that the flange and recess not only restrict undesirablerotation of the sleeve, they also usefully protect the disc brake fromoperator assembly error.

The sleeve portion and receiving portion of the rotation fixing maycomprise any suitable corresponding non-circular cross-sectionalprofiles to at least restrict the rotation of the sleeve relative to thebrake carrier. The corresponding non-circular cross-sectional profilesmay comprise at least one circular region and/or at least one linearregion, may have a regular and non-circular shape, may have an angularshape or a non-uniform shape.

In the alternative embodiment of the guide assembly depicted in FIG. 9athe sleeve portion 100 comprises a non-circular cross-sectional profilewith a flat, linear edge 102. The receiving portion 200 is a recessdisposed in the brake carrier with a corresponding non-circularcross-sectional profile with a flat, linear edge 202 to receive thesleeve portion. In the embodiment depicted in FIG. 9b , the sleeveportion 100 comprises a hexagonal cross-sectional profile 104. Thereceiving portion 200 is a recess disposed in the brake carrier with acorresponding hexagonal cross-sectional profile 204. In the embodimentdepicted in FIG. 9c , the sleeve portion 100 comprises a free-formcross-sectional profile 106. The receiving portion 200 is a recessdisposed in the brake carrier with a corresponding free-formcross-sectional profile 206.

The rotational fixing means may additionally or alternatively comprisean interconnection to interlock the sleeve and brake carrier so as torestrict rotation of the sleeve relative to the brake carrier. Theinterconnection may be locatable between a sleeve portion and receivingportion of a brake carrier.

The interconnection may comprise any suitable interconnection forrotationally engaging the sleeve and brake carrier. The interconnectionmay comprise a pin 300, for example as depicted in FIG. 9d . The sleeveportion 100 is received in the receiving portion 200. The pin 300extends in axial direction A and the opposing ends of the pin arereceived in recesses formed in the sleeve portion and brake carrier 10.The interconnection may comprise a ball 302, for example as depicted inFIG. 9e . The sleeve portion 100 is received in the receiving portion200. Opposing sides of the ball are received in semi-circular recessesformed in the sleeve portion and brake carrier 10. The interconnectionmay comprise a male protrusion and corresponding female indent. Forexample, as depicted in FIGS. 9f and 9g , the interconnection comprisesone or more blades 304 or teeth 306 extending in axial direction A fromthe end of the sleeve portion 100 into corresponding indents in thebrake carrier 10.

The rotational fixing means may comprise a deformable sleeve portion anda receiving portion for receiving the deformable sleeve portion. Thedeformable sleeve portion is configured to deform as it is located inthe receiving portion so as to form an interference fit/press fitconnection. Any rotation of the sleeve relative to the brake carrier isat least restricted due the interference fit/press fit connection.

The rotational fixing means may comprise a sleeve portion, a receivingportion to receive the sleeve portion and a friction enhancer to enhancethe frictional engagement between the sleeve portion and receivingportion and thereby restrict rotation of the sleeve with respect to thebrake carrier. The friction enhancer may comprise a knurled surface ofthe sleeve portion to enhance the frictional grip of the sleeve portion.The friction enhancer may comprise a splayed surface of the sleeveportion to help retain the sleeve portion in the receiving portion. Thefriction enhancer may comprise adhesive to bond the sleeve portion inthe receiving portion. The friction enhancer may comprise a washerlocatable between the sleeve portion and receiving portion. The washermay comprise a high friction washer and/or a toothed washer.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A rotational fixing for a disc brake, therotational fixing comprising: a guide pin having a guide sleeve; a brakecarrier having a receiving portion that receives a portion of the guidesleeve; and a friction enhancer between the brake carrier and the guidesleeve, wherein the friction enhancer provides frictional engagementbetween the guide sleeve and the brake carrier such that the frictionenhancer restricts rotation of the guide sleeve relative to the brakecarrier when the portion of the guide sleeve is received in thereceiving portion.
 2. The rotational fixing of claim 1 wherein the guidesleeve includes a circumferential flange or rim arranged at a first endof the guide sleeve, and the friction enhancer is located on thecircumferential flange or rim.
 3. The rotational fixing of claim 2wherein the friction enhancer is a knurled surface.
 4. The rotationalfixing of claim 3 wherein the knurled surface is provided on an end faceof the circumferential flange or rim.
 5. The rotational fixing of claim3 wherein the knurled surface is provided on a circumferentially outersurface of the circumferential flange or rim.
 6. The rotational fixingof claim 1 wherein the friction enhancer is located on the brakecarrier.
 7. The rotational fixing of claim 6 wherein the frictionenhancer is a knurled surface.
 8. The rotational fixing of claim 1wherein the friction enhancer includes a washer disposed between theguide sleeve and the receiving portion.
 9. The rotational fixing ofclaim 8 wherein the washer is a high friction washer.
 10. The rotationalfixing of claim 8 wherein the washer is a toothed washer.